A substrate with a transparent electrode, in which a transparent electrode layer is formed on a transparent substrate such as a film or glass, is used as a transparent electrode of a display of a touch panel or the like. Particularly, when the substrate with a transparent electrode is used for position detection of a capacitance touch panel, the transparent electrode layer is finely patterned. As a patterning method, for example, a method is used in which after a transparent electrode layer is formed substantially over the entire surface of a transparent substrate, the transparent electrode layer is removed by etching or the like in a part of the plane. In this way, a substrate with a transparent electrode in which a transparent electrode layer patterned into an electrode layer-formed part (also referred to as a “non-etched part”) and an electrode layer-non-formed part (also referred to as an “etched part”) is formed on a substrate can be obtained.
For clearly displaying an image on a display, it is important to improve the transparency and chromaticity of the substrate with a transparent electrode. Further, in the substrate with a transparent electrode, in which the transparent electrode layer is patterned, it is required that the pattern of the transparent electrode layer be hardly visible.
For example, Patent Documents 1 and 2 propose a substrate with a transparent electrode in which a transparent electrode layer is formed on a transparent film substrate with two dielectric material layers interposed therebetween. Patent Document 1 proposes that by setting the thickness and refractive index of each dielectric material layer to specific values, a difference in transmittance and a Δb* between an electrode layer-formed part and an electrode layer-non-formed part are reduced. Patent Document 2 proposes that by setting the thickness and refractive index of each dielectric material layer to specific values, a difference in reflectance between an electrode layer-formed part and an electrode layer-non-formed part is reduced to suppress visibility of a pattern.
Here, the chromaticity is a value defined by JIS Z8730, and can be represented by a CIE lightness L* and color coordinates a* and b*. The a* axis represents green to red, where the negative corresponds to green and the positive corresponds to red. The b* axis represents blue to yellow, where the negative corresponds to blue and the positive corresponds to yellow. A difference in chromaticity between two rays of light can be evaluated by a color difference ΔE represented by the following formula.ΔE={(ΔL*)2+(Δa*)2+Δb*)2}1/2 
For suppressing visibility of the pattern of the transparent electrode layer, it is necessary that the color difference between the electrode layer-formed part and the electrode layer-non-formed part be small for both transmitted light and reflected light. As is evident from the above formula, it is required to reduce not only Δb* but also ΔL* and Δa* for reducing the color difference ΔE.
In Patent Document 1, Δb* of transmitted light is small, but a difference in transmittance at each wavelength range and ΔL* and Δa* are not considered. Patent Document 2 discloses that a difference in reflectance in a wavelength range of 450 to 650 nm is reduced, but a difference in reflectance in wavelength ranges of 380 to 450 nm and 650 to 780 nm which are other visible light regions is not considered.
Patent Documents 3 and 4 disclose that a substrate with a transparent electrode, which includes three thin film layers having a specific thickness and a specific refractive index between a transparent film substrate and a transparent electrode, has a high transmittance and has transmitted light b* in a specific range. However, Patent Documents 3 and 4 disclose a substrate with a transparent electrode, which is principally used in a resistive touch panel, and do not discuss visibility of a pattern when the transparent electrode layer is patterned.